我有一個 python 函數它計算可能的硬幣變化量。每個硬幣的可用性有限。我試圖理解它以將其轉換為java但我在該行失敗了r=有人可以解釋這一行發生了什么嗎？# cs is a list of pairs (c, k) where there's k# coins of value c.def limited_coins(cs, n):? ? r = [1] + [0] * n? ? for c, k in cs:? ? ? ? # rs[i] will contain the sum r[i] + r[i-c] + r[i-2c] + ...? ? ? ? rs = r[:]? ? ? ? for i in xrange(c, n+1):? ? ? ? ? ? rs[i] += rs[i-c]? ? ? ? ? ? # This line effectively performs:? ? ? ? ? ? # r'[i] = sum(r[i-j*c] for j=0...k)? ? ? ? ? ? # but using rs[] so that the computation is O(1)? ? ? ? ? ? # and in place.? ? ? ? ? ? r[i] += rs[i-c] - (0 if i<c*(k+1) else rs[i-c*(k+1)])? ? return r[n]for n in xrange(50):? ? print n, limited_coins([(1, 3), (2, 2), (5, 3), (10, 2)], n)